Problem with code running

function prm = path_planner

% Import Obstacle Locations
filename ='Simple2Obst.txt';
delimiterIn = ' ';
headerlinesIn = 0;
rawdata = importdata(filename,delimiterIn,headerlinesIn);
object_coord = rawdata(1:2:1000);

% Draw Course
map = figure;
course_outx=[-2,-4,-6,-6, 6,6,4,2];
course_outy=[ 0, 0, 0,12,12,0,0,0];
hold on;
plot(course_outx,course_outy,'k','LineWidth',5);
axis([-7,7,-6,13]);
axis equal
set(gca,'XTick',-13:1:13)
set(gca,'YTick',-6:1:13)
grid ON

obst.ball = {};

% Tile the obstacles with balls
count = 1;
for i=1:2:500
    if (object_coord(i,1)<999)

        onew.p = [object_coord(i,1);object_coord(i+1,1)];   % line 29
        onew.r = 1/3;
        onew.handle = [];
        obst.ball{end+1} = onew;
        circle(onew.p(1,1),onew.p(2,1),onew.r,'b');
    end
end

I am trying to run this code but as it reaches to line 29 it says "Index increses matrix dimension.

I donot know how to solve this problem.

Index exceeds matrix dimensions.

Error in RRTpathplan (line 29)
        onew.p = [object_coord(i,1);object_coord(i+1,1)];

It says this